This invention was created to fill a void in the lens making field, that is, the efficient production of high quality toric lenses of small dimension. Previous to this invention there was no known device or system which could repeatedly mass produce the toric lenses to the precision required. The precision toric lenses produced by this invention are required at least in situations where two orientations of an astigmatic light beam must be focused differently in order to produce a useable image on the plane of focus. This invention produces a lens which at least can provide two foci as lines, separated by a specified distance, at a specified mean focal length. The most immediately recognized use of such lenses is for the purpose of providing electronic servo information as developed by Briscot et al (1976), in "Optical Readout of Videodisc" IEEE Transactions-Consumer Electronics (CE-22,304). Also, a lens of the type produced by this invention could be used to replace lenses like those described in U.S. Pat. No. 4,027,952, issued to Hugues. Unlike the lenses in Hughes, however, the lenses produced by this invention have one active optical surface with two curvatures. Likewise, patents by McLeod, U.S. Pat. No. 2,146,905 and Ross, U.S. Pat. No. 2,120,263 show alternate uses for toric lenses.
Other methods and systems have been devised for producing toric lenses, but none have provided the ease of use, quantity of throughput, or accurate centration which is available from the invention described herein. For example, U.S. Pat. No. 3,117,396 issued to Dalton, acknowledges the introduction of elipticity into lenses using its teachings (at lines 39-56). Some, for example, U.S. Pat. No. 3,900,972, issued to Rupp, can produce only concave torics lenses, whereas the invention taught herein produces convex surfaces.
Also, all art known to the inventor is useful for production of opthalimic lenses of a size roughly 38 mm to 150 mm in diameter with similar focal lengths, unlike this invention which is useful for production of higher quality lenses with a focal length on the order of 20 to 120 millimeters. The production of larger or smaller machines of similar construction to this invention would obviously produce larger or smaller lenses than those described herein with a high degree of accuracy, but the system described herein was engendered to produce smaller lenses than available from opthalmic lens machines.